The idea came to me after having success in a fighting event with an uber defensive deck, but I'm not sure if the ELO-friendly version of that Extended25 deck will work as well in SurvivorELO. The objective is to be able to turn a match in one round only, and I would very much appreciate the insight of more experienced Survivors.

Not really an experienced player, but my opinion is that perhaps you should switch Quinn out for something else that is not condition-based to better suit the purpose of being able to turn the match in any round at all.